The present disclosure relates to a semiconductor device, and more particularly to a semiconductor device including a plurality of fine metal wires connecting electrodes on a semiconductor chip to inner leads.
In recent years, electronic devices, such as mobile phones, DVD recorders/players, digital televisions, and car navigation systems, have achieved miniaturization, enhanced performance, and a larger number of functions. With this trend, the semiconductor device industry has required packaging technology which enables a high pin count, a small size, high density, and a reduced cost. Even when electrodes arranged at a finer pitch are connected to inner leads through fine metal wires during an assembly process, and as a result, the fine metal wires are deformed due to injection of a resin encapsulant during an encapsulation process, semiconductor devices enabling a reduced pitch can be manufactured at a low cost as long as the pitch between the adjacent fine metal wires can be maintained sufficiently large.
For example, Japanese Patent Publication No. 2001-345339 teaches a semiconductor device in which, to address this problem, a plurality of semiconductor chips are mounted in a stacked configuration on an island of a lead frame, and pins provided on the semiconductor chips are connected to inner leads of the lead frame through fine metal wires.
A conventional semiconductor device will be described with reference to the drawings.
FIG. 9 illustrates a cross-sectional view showing a part of a structure in which electrodes on a plurality of semiconductor chips are electrically connected to inner leads, and FIG. 10 illustrates a plan view showing a part of a structure in which the electrodes on the semiconductor chips are electrically connected to the inner leads through fine metal wires.
FIG. 9 shows a structure in which semiconductor chips 105A, 105B, and 105C are sequentially stacked on an island 102 of a lead frame 103, and first bond points 107A, 107B, and 107C respectively on electrodes of the semiconductor chips 105A, 105B, and 105C are respectively connected to second bond points 111A, 111B, and 111C on an inner lead 101 through fine metal wires 108, 109, and 110.
The conventional fine metal wires have trapezoidal shapes (bend shapes), which are trapezoidal portions 108b, 109b, and 110b, respectively continuous from first bending points 108a, 109a, and 110a. The fine metal wires except the upper fine metal wire 110 further respectively include third bending points 108e and 109e formed in slope potions following the second bend portions 108c and 109c, slope portions 108d and 109d located adjacent to the trapezoidal portions, and slope portions 108f and 109f located adjacent to the inner leads.